It's not there.
I have been trying to change my imessage Mac OS from stop sending old icloud email's from that account and changing to my number.
iPhone 11, iOS 15
Those settings live within the Messages app and cannot be found in System Settings. Open Messages, then click on "Messages" in the menu bar and select "Settings."
While in settings, you will see the General tab by default. Up at the top of the settings window click on the "@" that says "iMessage" underneath it. Here you will find settings for which iCloud account is logged into Messages, and you can make changes to which emails and phone numbers you want to be associated with your messages.
Those settings live within the Messages app and cannot be found in System Settings. Open Messages, then click on "Messages" in the menu bar and select "Settings."
While in settings, you will see the General tab by default. Up at the top of the settings window click on the "@" that says "iMessage" underneath it. Here you will find settings for which iCloud account is logged into Messages, and you can make changes to which emails and phone numbers you want to be associated with your messages.
mac os ventura 13.4.1 doesn't have imessage setting's to be able to change send & receive
